Package org.apache.lucene.index

Class ReaderUtil

java.lang.Object

org.apache.lucene.index.ReaderUtil

public final class ReaderUtil
extends Object

Common util methods for dealing with IndexReaders and IndexReaderContexts.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final record	ReaderUtil.PartitionedHits	Result of partitioning doc IDs by leaf, including the original input ordinals for scatter/gather.

Method Summary

Modifier and Type	Method	Description
static IndexReaderContext	getTopLevelContext(IndexReaderContext context)	Walks up the reader tree and return the given context's top level reader context, or in other words the reader tree's root context.
static ReaderUtil.PartitionedHits	partitionByLeaf(int[] globalDocIds, List<LeafReaderContext> leaves)	Partitions global doc IDs by leaf, tracking each doc ID's original position in the input array so callers can reassemble per-leaf results back to input order (scatter/gather).
static int	subIndex(int n, int[] docStarts)	Returns index of the searcher/reader for document n in the array used to construct this searcher/reader.
static int	subIndex(int n, List<LeafReaderContext> leaves)	Returns index of the searcher/reader for document n in the array used to construct this searcher/reader.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

getTopLevelContext

public static IndexReaderContext getTopLevelContext(IndexReaderContext context)

Walks up the reader tree and return the given context's top level reader context, or in other words the reader tree's root context.

subIndex

public static int subIndex(int n,
 int[] docStarts)

Returns index of the searcher/reader for document n in the array used to construct this searcher/reader.

subIndex

public static int subIndex(int n,
 List<LeafReaderContext> leaves)

Returns index of the searcher/reader for document n in the array used to construct this searcher/reader.

partitionByLeaf

public static ReaderUtil.PartitionedHits partitionByLeaf(int[] globalDocIds,
 List<LeafReaderContext> leaves)

Partitions global doc IDs by leaf, tracking each doc ID's original position in the input array so callers can reassemble per-leaf results back to input order (scatter/gather).

Doc IDs may be supplied in any order (e.g., ranking order); within each leaf the returned doc IDs are sorted in ascending order. For every partitioned doc ID the result also records its index in the original globalDocIds array, so callers can map per-leaf results back to input order. Callers that do not need the ordinals can simply ignore ReaderUtil.PartitionedHits.ordinalsByLeaf() and use ReaderUtil.PartitionedHits.docIdsByLeaf().

The input array is not mutated.

Parameters:

globalDocIds - global doc IDs in any order (e.g., ranking order)

leaves - the index reader's leaves

Returns:

per-leaf sorted doc IDs alongside per-leaf ordinals into the input array